Internal measuring instrument



y 7, 1953 G. BELLSTAEDT 2,644,239

INTERNAL MEASURING INSTRUMENT Filed May 16, 1952 Patented July 7, 1953 UNITED STATES PATENT OFFICE 4 Claims.

sion of a new and improved instrument for measuring or gaging the internal dimensions of hollow articles or members, that is, for example, the

height or width of a box-like structure, or the diameter of a cylindrical article, as well as numerous other applications. With this instrument the distanc between two walls may not only be gaged or measured, but it is also possible to check accurately whether the said distance is constant at all or various positions along the surfaces of the two walls.

The above broad as well as additional and more specific objects will be clarified in the following description wherein characters of reference refer to like-numbered parts in the accompanying drawing. It is to be noted that the drawing is intended solely for the purpose of illustration and that it is therefore neither desired nor intended to limit the invention necessarily to any or all of the exact details of construction shown or described except insofar as they may be deemed essential to the invention.

Referring briefly to the drawing,

Fig. 1 is a perspective view of the instrument embodying this invention.

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken on the line 3--3 of Fig. 2.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2.

Fig. 5 is a side view taken on the line 5-5 of Fig. 2, with parts broken away and partly in section.

Referring in detail to the drawing, the numeral It indicates a hollow tube or barrel open at both ends and paving a longitudinal slot I I in the bottom thereof on one side of the midpoint of the barrel, and a second and like longitudinal slot I2 in the bottom thereof on the other side of the said midpoint, the two slots being separated by the unslotted barrel bottom wall portion I3 which extends alike distance in both longitudinal directions from the said midpoint. Thus, both slots I I and I2 lie in a common plane through the axis of the barrel I0. A partition I4, which may be simply a rivet passing diametrically through the barrel at its midpoint, serves to divide the barrel into two compartments, both identical, shown at I5.

Slidably mounted in the ends of the barrel are plugs I6 tapering toward their outer extremities into tips I'I. Secured to each plug I6 near the inner end thereof is a plate I8 having a reduced portion I9 passing through the slot II or I2 and anchoredto or in the plug, with the plates I8 both lyingin the said plane through the slots I I and I2.

A pair of like less 20, which may be hollow, have each one end bifurcated and, by means of a rivet or the like 2 I, pivotally attached to a plate I8. The other ends of the legs 20 are formed, in a well-known manner, intoopposed pairs of ears 22 and 23 provided with aligned openings through which a pivot pin 24 passes; thus at the said other ends the legs 20 are mutually pivoted on the pin 24. A yoke 25, having the saddle. 26 and the two spaced parallel arms 21 extending from the saddle, is provided with aligned openings through the said arms, through which the pivot pin 24 also passes. A threaded stem 28, rigid with and at right angles to the saddle 26, extends from the latter and is provided at its outer end with a knurled nut 29.

A U-shaped rider plate 30 has a central passage 3i through the middle thereof between the legs 32 of the rider. A rounded cut-out 33 in the rider forms the two legs 32, and the inner surfaces of these legs press upon and engage the tubular legs 23. In each compartment I5 of the barrel It an expansion spring 34 is positioned between a plug I6 and the partition I4, thus urging the plugs outward and hence urging the legs 29 to spread apart about their common pivot 24. This the legs 253 will do until their other ends are stopped from spreading by the legs 32 of the rider 30. Thus, when the nut 20 is screwed down on the stem 28 the legs 32 will force the arms 20 to move closer together against the force of the springs 34, and conversely, when the nut 29 is unscrewed the receding rider 30 will permit the springs 34 to spread the arms 20. As a reinforcement of the hollow arms 20 at the areas against which the legs 32 forcibly engage, solid filler plugs 35 may be mounted in the lower ends of the arms 20..

In order to increase the distance of travel permitted the rider 30 in a direction toward the yoke 25, and owing to the curvature of the legs 32 resulting from the cut-out 33 which causes the legs 32 to widen gradually toward the body of the rider, both arms 20 are provided on their outer sides at their lower ends, with slots 36 in which the portions of the inner edges of the legs 32 register when the rider has been forced down sufiiciently far. If the slots 36 were not provided, the inner rounded edges of the legs 32 would engage the ends of the arms 20 at such a position of the rider and thus prevent the inner surfaces of the ends of the legs 32 from engagin the arms in which case the rider would be unable to bring the'arms 20 closer together beyond that point.

Graduations are provided on the barrel as follows. The graduation zero, shown at 31, is marked at the midpoint of the barrel, that is, in the transverse plane in which the partition Id lies. Onone side 31a of the zero mark, the bar reel is graduated in inches, and on the other side 38 the barrel is graduated in centimeters and millimeters.

In use, the nut 29 is screwed down or up until the tips ll of the plugs [B are so spaced as to readily permit insertion of the barrel between the walls whose spacing is to be measured. Then the nut is loosened sufficiently to bring the tips 16 into engagement with the opposite walls. The instrument is then removed and the distance between the tips 16 is measured or read on the graduated barrel. To facilitate reading of the graduations on the barrel, arcuate indicators or fingers 39 are attached to the plates 18 to slide along the barrel. I

Obviously, modifications in form or structure may be made without departing from the spirit or scope of the invention.

I claim:

1. A measuring instrument comprising a hollow barrel having plugs slidably mounted in the ends thereof, a transverse partition through the midpoint of the barrel, expansion springs in the barrel positioned between said partition and said plugs normally urging said plugs outward from the barrel, said barrel having spaced slots through the bottom thereof on the sides of said partition and lying in a common plane through the axis of the barrel, lugs anchored to said plugs and extending through said slots, a pair of arms each having one end pivoted to one of said lugs, the other ends of said arms having ear-s thereon, a pivot pin extending through the ears of both of said arms thereby pivotally join- 'mg said arms at said other ends thereof, a yoke 4 including a saddle and two parallel legs, a threaded stem extending from said saddle and having a nut threaded thereon, said yoke legs be- 7 ing positioned between said ears and having said pivot pin passing therethrough, a rider plate having a rounded cut-out providing two legs thereon and having a passage therethrough midway between and parallel with said rider legs, said stem passing loosely through said rider passage and positioning said rider slidably on said stem between said saddle and said nut, the inner edges of the extremities of said rider legs engaging said arms and limiting the spreading of said arms about said pivot pin, said arms thereby being adapted to be brought closer together by tightening said nut on said stem and to be spread farther apart owing to the force of said springs by loosening said nut.

2. The instrument set forth in claim 1, said barrel having longitudinally arranged graduations thereon including a zero graduation at the midpoint of the barrel and ascending graduations in both longitudinal directions from said midpoint, and indicator fingers on said lugs.

3. The instrument set forth in claim 1, said arms being hollow and having solid filler plugs in said other ends thereof against which said legs or said rider plate bear.

4. The instrument set forth in claim 1, said other ends of said arms having slots therein lying in the plane of said rider plate, those portions of the inner edges of said rider legs distant from the extremities thereof being registrable insaid last-named 5101's when said rider plate has been moved a given distance toward the barrel by screwing down said nut.

GUSTAV BELLSTAED References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,943,921 Larson 1- Jan. 16, 1934 2,573,075 v Watson 1 1 Oct. 30, 1951 

